Frequency values getting zero in modal analysis

[AISWARYA]

Hi,

I performed modal analysis in ansys mechanical and I got the frequency values zero. Can anyone help me to find why it is so?

Thanks 

Aiswarya

[Asdrubal Ayestaran]

Hi,

A zero-value frequency in a modal analysis represent a rigid mode, usually due to:

1. Your model is not constrained or has insufficient boundary conditions that prevents a rigid movement.

2. There are parts with no contacts defined or with nonlinear contacts outside the pinball radius tolerance. Remember that a modal analysis is a linear analysis, and nonlinear contacts are switched internally in ansys into the linear ones (bonded, no separation or "free") depending on the gap or separation between parts and the pinball region defined in every contact, sometimes a nonlinear contact could be set to "Free" to move even if you have defined previously.

Check the displacement results with an exaggerated scale in order to see which part of the model is free to move relative to other parts. Animating the result sometimes is useful to verify your model in a modal analysis.

Regards,

Asdrubal

[AISWARYA]

thank you for the response.